#include "raster.h"

Matrix
identity(void)
{
	Matrix m = {1.0f, 0.0f, 0.0f, 0.0f,
	            0.0f, 1.0f, 0.0f, 0.0f,
	            0.0f, 0.0f, 1.0f, 0.0f,
	            0.0f, 0.0f, 0.0f, 1.0f};
	return m;
}

Matrix
frustum(float l, float r, float b, float t, float n, float f)
{
	Matrix m = identity();
	m.cr[0][0] = (2.0f*n)/(r-l); 
	m.cr[1][1] = (2.0f*n)/(t-b); 
	m.cr[2][0] = (r+l)/(r-l);
	m.cr[2][1] = (t+b)/(t-b);
	m.cr[2][2] = -(f+n)/(f-n);
	m.cr[2][3] = -1.0f;
	m.cr[3][2] = -2.0f*f*n/(f-n);
	m.cr[3][3] = 0.0f;
	return m;
}

Matrix
perspective(float fov, float aspect, float n, float f)
{
	float r, t;
	r = n*tan(fov*3.14159f/360.0f);
	t = r/aspect;
	return frustum(-r, r, -t, t, n, f);
}

Matrix
mulmat(Matrix a, Matrix b)
{
	int i, j;
	Matrix out;
	for(i = 0; i < 4; i++)
		for(j = 0; j < 4; j++)
			out.cr[i][j] = a.cr[0][j]*b.cr[i][0] +
			               a.cr[1][j]*b.cr[i][1] +
			               a.cr[2][j]*b.cr[i][2] +
			               a.cr[3][j]*b.cr[i][3];
	return out;
}

Vector4
mulmatvec(Matrix m, Vector4 v)
{
	int i;
	Vector4 out;
	for(i = 0; i < 4; i++)
		out.e[i] = m.cr[0][i]*v.x +
		           m.cr[1][i]*v.y +
		           m.cr[2][i]*v.z +
		           m.cr[3][i]*v.w;
	return out;
}

Matrix
translation(float x, float y, float z)
{
	Matrix m = identity();
	m.cr[3][0] = x;
	m.cr[3][1] = y;
	m.cr[3][2] = z;
	return m;
}

Matrix
rotationX(float a)
{
	Matrix m = identity();
	m.cr[1][1] = cos(a);
	m.cr[1][2] = sin(a);
	m.cr[2][1] = -sin(a);
	m.cr[2][2] = cos(a);
	return m;
}

Matrix
rotationY(float a)
{
	Matrix m = identity();
	m.cr[0][0] = cos(a);
	m.cr[2][0] = sin(a);
	m.cr[0][2] = -sin(a);
	m.cr[2][2] = cos(a);
	return m;
}

Matrix
rotationZ(float a)
{
	Matrix m = identity();
	m.cr[0][0] = cos(a);
	m.cr[0][1] = sin(a);
	m.cr[1][0] = -sin(a);
	m.cr[1][1] = cos(a);
	return m;
}